Reading Medicare Advantage share four to eight weeks before the quarter
CMS publishes every Medicare Advantage parent's enrollment monthly, mid-month, so a quarter's three prints exist before the quarter closes; this note reads the March to August 2026 series for eight listed insurers and one county each of share loss and share gain.
What the data is
CMS publishes enrollment for every Medicare Advantage and Part D contract by plan, state and county each month (the CPSC files). Healthparse rolls the file up to parent organization by program by county by month and attaches a ticker where the parent is listed. The national table used here is ma_enrollment_parent_monthly filtered to program = 'MA', which excludes stand-alone Part D, cost and PACE contracts. Six months are loaded, March to August 2026 (docs/data-dictionaries/medicare_advantage_enrollment.md).
The August 2026 file totals 35,530,809 MA enrollees across 166 parent strings. The March file totals 35,215,283. The six-month gain is 315,526, or 0.90%.
Timing
CMS posts a month's file around the 10th to 14th of that same month; January slips to mid-February (dictionary, refresh cadence). A calendar quarter therefore has all three of its monthly prints in the public domain before the quarter ends. For the September quarter, the July and August files are out and the September file is due mid-September. The insurer's reported quarter-end membership arrives with its quarterly report after quarter-end. Healthparse loads each file on the 2nd of the following month.
The reconciliation is direct: the June 2026 CMS print against each insurer's reported Q2 2026 Medicare Advantage membership. No reported Q2 2026 figure is held in this repository; the comparison column below was filled from each insurer's Q2 2026 earnings release on 2026-09-10.
National series, eight listed parents
MA enrollment, program = MA, national. One parent string per ticker in this window.
| Ticker | Mar 2026 | Apr | May | Jun | Jul | Aug | Mar to Aug | % |
|---|---|---|---|---|---|---|---|---|
| UNH | 9,257,606 | 9,233,670 | 9,222,082 | 9,223,595 | 9,233,940 | 9,240,295 | -17,311 | -0.19% |
| HUM | 7,023,732 | 7,054,070 | 7,090,682 | 7,103,935 | 7,111,079 | 7,118,203 | 94,471 | 1.35% |
| CVS | 4,052,752 | 4,065,223 | 4,077,387 | 4,085,717 | 4,092,566 | 4,105,194 | 52,442 | 1.29% |
| ELV | 1,881,246 | 1,874,580 | 1,872,855 | 1,872,727 | 1,874,144 | 1,875,238 | -6,008 | -0.32% |
| CNC | 938,154 | 933,376 | 923,576 | 914,949 | 908,829 | 902,925 | -35,229 | -3.76% |
| MOH | 228,328 | 225,881 | 222,424 | 221,563 | 220,775 | 220,801 | -7,527 | -3.30% |
| ALHC | 280,685 | 283,886 | 288,194 | 290,827 | 292,928 | 294,957 | 14,272 | 5.08% |
| CLOV | 153,669 | 154,259 | 154,842 | 155,366 | 155,934 | 156,365 | 2,696 | 1.75% |
| All MA | 35,215,283 | 35,271,470 | 35,348,685 | 35,404,146 | 35,464,025 | 35,530,809 | 315,526 | 0.90% |
Month-over-month change, count and percent:
| Ticker | Apr | May | Jun | Jul | Aug |
|---|---|---|---|---|---|
| UNH | -23,936 (-0.26%) | -11,588 (-0.13%) | +1,513 (0.02%) | +10,345 (0.11%) | +6,355 (0.07%) |
| HUM | +30,338 (0.43%) | +36,612 (0.52%) | +13,253 (0.19%) | +7,144 (0.10%) | +7,124 (0.10%) |
| CVS | +12,471 (0.31%) | +12,164 (0.30%) | +8,330 (0.20%) | +6,849 (0.17%) | +12,628 (0.31%) |
| ELV | -6,666 (-0.35%) | -1,725 (-0.09%) | -128 (-0.01%) | +1,417 (0.08%) | +1,094 (0.06%) |
| CNC | -4,778 (-0.51%) | -9,800 (-1.05%) | -8,627 (-0.93%) | -6,120 (-0.67%) | -5,904 (-0.65%) |
| MOH | -2,447 (-1.07%) | -3,457 (-1.53%) | -861 (-0.39%) | -788 (-0.36%) | +26 (0.01%) |
| ALHC | +3,201 (1.14%) | +4,308 (1.52%) | +2,633 (0.91%) | +2,101 (0.72%) | +2,029 (0.69%) |
| CLOV | +590 (0.38%) | +583 (0.38%) | +524 (0.34%) | +568 (0.37%) | +431 (0.28%) |
Share of national MA enrollment, March to August: UNH 26.29% to 26.01%; HUM 19.95% to 20.03%; CVS 11.51% to 11.55%; ELV 5.34% to 5.28%; CNC 2.66% to 2.54%; MOH 0.65% to 0.62%; ALHC 0.80% to 0.83%; CLOV 0.44% to 0.44%.
UNH lost enrollment in April and May and grew from June; August is still 17,311 below March. CNC declined every month, most in May and June. HUM added 66,950 across April and May and then slowed to about 7,000 a month.
Reconciliation to reported Q2 2026 membership
Reported figures are as of June 30, 2026, from each company's Q2 2026 earnings release (Exhibit 99.1 or 99.2 to Form 8-K on EDGAR, links below). Difference is reported minus CMS; percent is that difference over the CMS print. Company tables report in thousands; they are shown here in members.
| Ticker | Reported Q2 2026 MA members | CMS June 2026 print (MA) | Difference | % | Note |
|---|---|---|---|---|---|
| UNH | 7,565,000 | 9,223,595 | -1,658,595 | -17.98% | "Medicare Advantage" row of the People Served table, rounded to 5,000; the release describes it as seniors served through MA "including programs serving complex populations included in Medicaid"; Medicare Supplement (4,260,000) and Part D stand-alone (2,710,000) are separate rows; no group MA or D-SNP split. [1] |
| HUM | 7,180,900 | 7,103,935 | +76,965 | +1.08% | "Total Medicare Advantage": Individual MA 6,453,700 plus Group MA 727,200; individual MA includes 959,900 D-SNP members; stand-alone PDP (3,946,400) and Medicare Supplement (551,500) are separate. [2] |
| CVS | 4,202,000 | 4,085,717 | +116,283 | +2.85% | "Medicare Advantage" row of the medical membership table, all insured; Medicare Supplement (1,176,000) and stand-alone PDP (3,870,000) are separate; the release refers to a Group Medicare Advantage product line but does not split it out. [3] |
| ELV | 1,897,000 | 1,872,727 | +24,273 | +1.30% | "Medicare Advantage" row; Medicare Supplement (893,000) separate; no group or D-SNP split. [4] |
| CNC | 980,000 | 914,949 | +65,051 | +7.11% | "Medicare" row; footnote 4 states it includes Medicare Advantage, Medicare Supplement and Applicable Integrated Plans following the 2026 CMS D-SNP integration; former MMP duals are in this row from 2026; PDP (8,803,000) separate. Not a pure MA count. [5] |
| MOH | 224,000 | 221,563 | +2,437 | +1.10% | "Medicare" segment ending membership; no footnote on products included; the release says the company will exit its Medicare Advantage Prescription Drug product for 2027 to focus on dual eligibles. [6] |
| ALHC | 294,100 | 290,827 | +3,273 | +1.13% | "Health plan membership at the end of the quarter was approximately 294,100", described as Medicare Advantage membership. [7] |
| CLOV | 157,309 | 155,366 | +1,943 | +1.25% | "Insurance members" as of June 30, 2026, described as Medicare Advantage membership; the quarterly average was 156,840. [8] |
Sources, all read 2026-09-10:
- UnitedHealth Group, Q2 2026 earnings release, July 16, 2026, People Served table: https://www.sec.gov/Archives/edgar/data/731766/000073176626000191/earningsrelease2q26_7152.htm
- Humana, Q2 2026 detailed earnings release (Exhibit 99.2), July 29, 2026, Membership Detail: https://www.sec.gov/Archives/edgar/data/49071/000004907126000045/hum-2026q2xex99x2detailedx.htm
- CVS Health, Q2 2026 earnings release, August 5, 2026, Health Care Benefits medical membership: https://www.sec.gov/Archives/edgar/data/64803/000006480326000097/cvs_ex99x1q2-26.htm
- Elevance Health, Q2 2026 earnings release, July 15, 2026, medical membership table: https://www.sec.gov/Archives/edgar/data/1156039/000115603926000058/a2q2026elvearningsrelease.htm
- Centene, Q2 2026 earnings release, July 28, 2026, membership table and footnote 4: https://www.sec.gov/Archives/edgar/data/1071739/000107173926000154/a20260728ex991pressrelease.htm
- Molina Healthcare, Q2 2026 earnings release, July 22, 2026, ending membership by segment: https://www.sec.gov/Archives/edgar/data/1179929/000117992926000036/moh2q26_er.htm
- Alignment Healthcare, Q2 2026 earnings release, July 30, 2026: https://www.sec.gov/Archives/edgar/data/1832466/000117184326005078/exh_991.htm
- Clover Health, Q2 2026 earnings release, August 5, 2026, Lives under Clover Management: https://www.sec.gov/Archives/edgar/data/1801170/000180117026000196/a2q26exx991xearningsrelease.htm
Seven of the eight reported figures sit within 1% to 7% above the CMS print. UNH is the exception: its 7,565,000 is 1.66 million below the CMS parent total, and the release does not state what the company excludes, so that gap is not explained here. Two definitional differences to expect when reading the column. The parent string is CMS's, so a merger appears when CMS changes the string, not on the deal date. A company's reported figure may count group MA, dual-eligible SNP or Part D lives on a different basis from the program column.
One county of share loss and one of share gain
The parent-county pair with the largest absolute decline from March to August, across these eight parents, is Humana in Honolulu County, HI (FIPS 15003): 14,134 to 9,672, a drop of 4,462. This is not an exit. Humana's plan count in the county rose from 69 to 74 and its contract count from 9 to 11. The county's total MA enrollment across all parents was flat, 113,618 to 113,984. The decline came in two steps, March to April (14,134 to 12,196) and May to June (11,737 to 9,810). Over the same window Hawaii Medical Service Association rose 26,655 to 29,375 and Devoted Health 8,511 to 10,242. The data shows share moving inside a flat county; it does not say why.
The second largest decline is CVS Health in Spartanburg County, SC (45083): 6,243 to 3,042, in a single step from April to May (6,189 to 3,297), with the plan count steady at 91 to 94. Humana (18,311 to 19,994) and Devoted (3,733 to 5,133) rose in the same county.
The largest gain is Humana in Cook County, IL (17031): 144,889 to 147,854, up 2,965, with plan count 143 to 151. Alignment Healthcare in Los Angeles County, CA is next at 45,101 to 48,044, up 2,943.
Suppression caveat
CMS blanks any contract-plan-county cell with fewer than 11 enrollees. The rollup sums the unsuppressed cells and counts the suppressed plans per parent-county, so a county figure is a floor, not an estimate; each suppressed plan holds at most 10 enrollees. About 95% of raw cells are suppressed but they hold under 1% of enrollment, and national totals are unaffected in practice (dictionary). In Honolulu, Humana's suppressed plan count was 59 in March and 64 in August, so the floor could understate Humana by at most 640 in August. That bound does not close a 4,462 decline.
Appendix: queries
Run 2026-09-10 against the production Postgres over DIRECT_URL, read-only, statement_timeout = 60s. The county-level query filters on the indexed (parent_organization, program, report_month) columns. Month-over-month and share columns in the tables above are arithmetic on the query output.
-- National MA total by month
SELECT report_month, sum(enrollment) AS ma_total, count(*) AS parents
FROM ma_enrollment_parent_monthly WHERE program = 'MA' GROUP BY 1 ORDER BY 1;
-- National MA enrollment by ticker and month
SELECT t.ticker, m.report_month, sum(m.enrollment) AS enrollment,
sum(m.suppressed_plan_county_rows) AS suppressed_cells,
string_agg(DISTINCT m.parent_organization, ' | ') AS parents
FROM ma_enrollment_parent_monthly m
JOIN cms_ma_parent_tickers t USING (parent_organization)
WHERE m.program = 'MA'
AND t.ticker IN ('UNH','HUM','CVS','ELV','CNC','MOH','ALHC','CLOV')
GROUP BY 1, 2 ORDER BY 1, 2;
-- Largest county declines and gains, March to August, for the same parents
WITH p AS (SELECT parent_organization, ticker FROM cms_ma_parent_tickers
WHERE ticker IN ('UNH','HUM','CVS','ELV','CNC','MOH','ALHC','CLOV')),
fl AS (
SELECT r.parent_organization, p.ticker, r.fips_state_county, r.state, r.county,
max(r.enrollment) FILTER (WHERE r.report_month = '2026-03-01') AS mar_enr,
max(r.enrollment) FILTER (WHERE r.report_month = '2026-08-01') AS aug_enr,
max(r.plan_count) FILTER (WHERE r.report_month = '2026-03-01') AS mar_plans,
max(r.plan_count) FILTER (WHERE r.report_month = '2026-08-01') AS aug_plans,
max(r.suppressed_plan_count) FILTER (WHERE r.report_month = '2026-03-01') AS mar_supp,
max(r.suppressed_plan_count) FILTER (WHERE r.report_month = '2026-08-01') AS aug_supp
FROM ma_enrollment_parent_county_monthly r JOIN p USING (parent_organization)
WHERE r.program = 'MA' AND r.report_month IN ('2026-03-01','2026-08-01')
AND r.fips_state_county IS NOT NULL
GROUP BY 1, 2, 3, 4, 5)
(SELECT 'decline' AS kind, *, coalesce(aug_enr,0) - coalesce(mar_enr,0) AS chg FROM fl
ORDER BY chg ASC LIMIT 5)
UNION ALL
(SELECT 'gain' AS kind, *, coalesce(aug_enr,0) - coalesce(mar_enr,0) AS chg FROM fl
ORDER BY chg DESC LIMIT 5);
-- Monthly series for the three named parent-county pairs
SELECT report_month, parent_organization, fips_state_county, enrollment,
plan_count, contract_count, suppressed_plan_count
FROM ma_enrollment_parent_county_monthly
WHERE program = 'MA' AND (
(fips_state_county = '15003' AND parent_organization = 'Humana Inc.')
OR (fips_state_county = '17031' AND parent_organization = 'Humana Inc.')
OR (fips_state_county = '45083' AND parent_organization = 'CVS Health Corporation'))
ORDER BY 3, 1;
-- County total and parents in Honolulu (15003), Spartanburg (45083), Cook (17031)
SELECT report_month, sum(enrollment) AS county_ma_total
FROM ma_enrollment_parent_county_monthly
WHERE program = 'MA' AND fips_state_county = '15003' GROUP BY 1 ORDER BY 1;
SELECT parent_organization,
max(enrollment) FILTER (WHERE report_month = '2026-03-01') AS mar,
max(enrollment) FILTER (WHERE report_month = '2026-08-01') AS aug
FROM ma_enrollment_parent_county_monthly
WHERE program = 'MA' AND fips_state_county = '15003' -- repeated for 45083 and 17031
AND report_month IN ('2026-03-01','2026-08-01')
GROUP BY 1 ORDER BY 3 DESC NULLS LAST LIMIT 8;
Reported Q2 2026 membership: not queried. A grep of docs/ for reported membership figures for these eight companies returned nothing; the reconciliation column was filled from the eight earnings releases cited above on 2026-09-10.